Question

A Truck weighing 1000 kgf changes its speed from 36 km h⁻¹ to 72 km h⁻¹ in 2 minutes. Calculate (i) Work Done by the engine and (ii) its power (g=10ms⁻²)

Answer 1

Explanation:-

u=36 km h=36×5/18

u=10 m/s

v=72 km h=72×5/18

v=20 m/s

$\sf\;mass=1000\;kg\\\\w=\frac{1}{2}1000\times(20^2-10^2)\\\\w=500\times 300\\\\2=150000\;j\\\\w=1.5\times 10^4$

So the work done is 1.5×10^4 joules

$\sf\;2)power=\frac{work\;done}{time\;taken}\\\\Time=2\;minutes=120\;second\\\\Power=\frac{1.2\times 10^5}{120}\\\\Power=1.25\times 10^3$

So the work done is 1.25×10^3